In vivo press can be indicative of organ's function; for example, of endo luminal conditions. The pressure in blood vessels, intra cerebral pressure or intra-gastric pressure, for example, may be indicative of the activity in these body lumens or of prevailing conditions in these lumens. The gastrointestinal (GI) tract is a typically convoluted body lumen starting from the oral cavity and proceeding through the esophagus, stomach, duodenum and small intestine and ending at the rectum; it is a long tube that folds many times to fit inside the abdomen. The small intestine is connected to the large intestine, which begins with the cecum, a small saclike evagination, then continues through the ascending colon, transverse colon, descending colon and the sigmoid (S-shaped) colon to the rectum. Portions of the GI tract are separated by muscular valves, such as the esophageal gate, separating the esophagus from the stomach, the pylorus, separating the stomach from the small intestine and the ileocecal valve separating the cecum from the colon. Such gates may be considered “motility gates” in the sense that motility of matter moving through the GI system may differ before and after passing through such gates. Matter, such as food, is passively moved through the GI tract and pushed through the valves due to the muscle action of the GI tract wall, namely, peristalsis. Thus, motility in the GI tract is achieved via pressure exerted by the GI tract walls.
Some gastrointestinal conditions or diseases, for example constipation, GERD (gastroesophageal reflux disease) and IBS (irritable bowel syndrome), are thought to be related to intestinal motility and are some times referred to as functional diseases (either the muscles of the organs or the nerves that control the organs are not working normally, and, as a result, the organs do not function normally). Whereas some gastrointestinal diseases can be seen and diagnosed with the naked eye or by microscopic examination of biopsies gastrointestinal functional diseases typically cannot be seen with the naked eye or with the microscope. In some instances, the abnormal function can be demonstrated by tests, for example, gastric emptying studies or antro-duodenal motility studies. However, these tests often are complex, are not widely available, and do not reliably detect the functional abnormalities. Accordingly, functional gastrointestinal diseases are identified, to date, by default, namely, diseases involving the abnormal function of gastrointestinal organs in which abnormalities cannot be seen in the organs with either the naked eye or the microscope.
Endo-luminal pressure, e.g., gastric pressure, may be measured by pressure sensors carried on the end of endoscopes or catheters However, these methods may cause patient discomfort and are of limited scope (for example, these methods are not useful for sensing the entire GI tact). They also, by being interventionist in nature, may distort the normal behavior thus distorting the results. Gastric pressure has been known to be measured and the information transmitted from the body by an autonomous ingestible device including, for example, a diaphragm assembly, which includes a diaphragm and elements such as coils, capacitors and a transistor. This assembly, which may be housed in a plastic cap or in a rubber sack, is inserted into the GI tract such that vibration of the gastrointestinal environment (typically containing fluids) is sensed. These measurements and measurements of pressure sensors used in other methods may be useful for indicating the hydrostatic pressure in a body lumen. The hydrostatic pressure is exerted uniformly throughout the lumen, and as such, is easily influenced by events that are unrelated to the activity or condition of the lumen itself. For example, pressure sensed in the GI tract can be affected by breathing and heart activity.
There is therefore a need for an improved system and method for sawing in vivo environments for parameters such as pressure, which might be indicative of a body lumen activity and/or of its condition.